The surge in minority voting was even more pronounced in some election swing states, including Ohio, the liberal-leaning nonprofit group Project Vote reported.

Project Vote also said that the number of voters ages 18-29 increased by more than 1.8 million, the biggest jump of any similarly sized age group, reflecting a depth of support for Obama among younger voters.

The figures appear to reflect the success of Project Vote and other liberal voter registration groups in registering millions of young, poor, elderly and minority Americans to vote in recent election cycles.

Project Vote found itself in a firestorm of largely unsubstantiated allegations of voter fraud over its hiring of the Association of Community Organizations for Reform Now to register voters this year, but the group nonetheless reported submitting 1.3 million applications. It estimates that 70 percent of them resulted in new or updated registrations.

Based on exit polling data, Project Vote estimated that the nationwide African-American vote rose by 2.88 million, to 16.3 million, accounting for 13 percent of the ballots compared with 11 percent in 2004. The Latino turnout increased by 1.5 million to 11.3 million, accounting for 9 percent of the total ballots, up from 8 percent, the group said.

In addition, an estimated 67,000 more Asian Americans cast ballots this year than in 2004, and 1.3 million more minorities of other races, including biracial individuals, voted this year.

According to the analysis, 538,000 fewer Ohio whites voted this year than in 2004, an 11 percent drop. At the same time, Project Vote reported, 12.8 percent more African Americans, or an increase of 66,000 over 2004, and 22.7 percent more Latinos, a jump of 39,000, voted in Ohio.

Obama won the state's 20 electoral votes by fewer than 207,000 votes, a big triumph after President George W. Bush carried Ohio in both 2000 and 2004.

While nationwide voter turnout rose by less than 3 percent in the 2008 election, "the composition of voters changed significantly," said Michael Slater, Project Vote's executive director. "It's grown more diverse.

"One candidate, John McCain, was unable to reach out to this broad electorate and was unable to mobilize the traditional Republican base of supporters."

Slater also said that it seems "fair to speculate that Obama did not pick up all the Clinton supporters he might have wanted to," referring to white, blue-collar voters who heavily backed New York Sen. Hillary Clinton in the fight for the Democratic nomination. "On the other hand, McCain didn't get them either, because it looks like many of them may have stayed home."

In Florida, whose 27 electoral votes Obama pried away from Republicans after Bush won the state in 2000 and 2004, the number of white voters rose by 654,000, nearly keeping pace with a 13 percent rise in the state's population, the group said. According to the analysis, Florida's African-American vote rose by 182,000, or nearly 20 percent. Its Latino vote also increased, by 38,000, or 3 percent.

In Missouri, the African-American vote soared 74 percent, to 380,000, in a state whose final presidential-election results were still up in the air on Tuesday, with McCain leading by more than 4,000 votes.

Surges in minority voting in Colorado, Nevada and New Mexico also appear to have boosted Obama. In Colorado, the Latino vote rose by 132,000, or 72 percent, helping Obama win by fewer than 200,000 votes. In Nevada, the African-American vote rose by 39,000, and the Latino vote by 72,000, or 87 percent, as Obama won the state by 120,000 votes, and in New Mexico, an increase of 92,000 Latino voters, or 37 percent more than in 2004, helped Obama win by 120,000 votes.

Project Vote said it conducted its analysis from exit polling data reported by CNN.com and gathered by Edison Media Research in 2008 and by Edison/Mitofsky Research in 2004.